A record number of passengers are expected at U.S. airports this Thanksgiving holiday, as low fares and a growing economy fuel a surge in air travel.

An estimated 27.3 million will fly during the 12-day Thanksgiving period, according to industry trade group Airlines for America, an increase of 700,000 passengers compared to last year.

“We believe this to be an all time high up from the previous all time high of last year,” Airline for America’s chief economist John Heimlich said.

The busiest days for travel will be the Sunday and Monday after Thanksgiving, followed by the Wednesday before the holiday. The lightest travel day will be Thanksgiving day.

Many of those passengers will be traveling through DFW, which is projected to be the fourth busiest airport during the Thanksgiving holiday, behind airports in Atlanta, Los Angeles and Chicago.

And while those airports will be crowded, there aren't the same concerns about excessive security line waits that cropped up around Memorial Day. Since then, airlines and the Transportation Security Administration have been working to increase staffing to help keep the lines moving.

Travelers are being lured to airports with some of the cheapest fares in years due to increased competition between airlines, an oversupply of seats and low fuel prices. Overall, average fares have fallen 5.6 percent so far in 2016, according to Airlines for America.

“Not surprisingly, with the expanding economy and the reduction in fares amid a competitive airline environment, we saw a 3.2 percent increase in passenger traffic (in 2016),” Heimlich said.

That increase in passenger traffic has been outpaced by the growth in the number of seats on the market, which increased 3.7 percent in the domestic market in 2016, approaching pre-recession highs.

The imbalance between the number of passengers and the number of available seats has pushed fares lower. But that trend likely won’t last much longer, with U.S. airlines signaling that they’ll slow their growth through the end of this year and into 2017 in an attempt to bring supply more in line with demand.

That, in turn, is expected to halt the decline of fare prices and slowly start pushing them back up.

Bringing in more revenue from fares will be important as airlines see increasing labor costs, which were up 8.5 percent industry wide through the first nine months of 2016.

So far low fuel costs, which are down 22 percent this year, have helped make up for higher labor and aircraft expenses. But fuel prices have been steadily rising and airline executives expect they’ll be paying more in 2017.

For now, airlines are still enjoying a streak of continued profitability, with $18.3 billion in pre-tax income through the first nine months of 2016, a slight drop from the $18.7 billion they earned over that same period in 2015.